The present invention relates to a multilayered tubular synthetic sausage casing comprising an outer layer based on polyamide, an inner layer of polyolefin which is in contact with the enclosed matter, i.e., in particular, with the sausage meat, and an intermediate layer, by means of which the outer and inner layers are bonded to one another.
Conventional packaging casings of this general type have the disadvantage that following the simmering or cooking of the casing stuffed with sausage meat the internal casing wall is no longer in contact with the sausage meat. Hollow spaces have formed between the sausage meat and the casing, as a result whereof liquid constituents may exude from the sausage meat and penetrate into these hollow spaces. The casing no longer surrounds the sausage meat tightly and closely, but has a creased appearance. After the cooling down of the sausage, undesired jelly pockets form in the interspace between the casing and the sausage meat, giving the sausage such an unattractive appearance that it can no longer be offered for sale.
According to DE-A-33 08 296, this problem is said to be overcome by keeping the outer polyamide layer of a tubular casing having the above described layer build-up in a crystallized and moistened state. Following the tight stuffing of the tubing with a hot, pasty foodstuff, the outer polyamide layer dries out, so that following the cooling down, the tubular casing is said to shrink elastically and tightly onto its contents. This process is, however very complicated and has not gained general acceptance in practice.
According to the teaching of DE-A-38 16 942, the formation of creases can be avoided by treating the internal layer of polyolefin resin with a corona discharge and optionally applying starch powder to it. U.S. Pat. No. 4,606,922 provides still another solution to the problem. According to this patent, an ionomer that can be treated with ionizing radiation is used for the internal side of the casing. These more recently proposed solutions have the disadvantage that an additional treatment of the polyolefin layer is required to prevent the formation of creases and jelly pockets.